ring-buffer: Get timestamp after event is allocated

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Move the capturing of the timestamp to after an event is allocated.
If the event is not a commit (where it is an event that preempted
another event), then no timestamp is needed, because the delta of
nested events is always zero.

If the event starts on a new page, no delta needs to be calculated
as the full timestamp will be added to the page header, and the
event will have a delta of zero.

Now if the event requires a time extend (the delta does not fit
in the 27 bit delta slot in the header), then the event is discarded,
the length is extended to hold the TIME_EXTEND event that allows for
a 59 bit delta, and the commit is tried again.

If the event can't be discarded (another event came in after it),
then the TIME_EXTEND is added directly to the allocated event and
the rest of the event is given padding.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

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This commit is contained in:

Steven Rostedt (Red Hat) 2015-05-29 09:40:18 -04:00 • committed by Steven Rostedt

parent 9826b2733a

commit a4543a2fa9

1 changed files with 114 additions and 47 deletions

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kernel/trace/ring_buffer.c

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